2. HISTOEICAL DEVELPPMENT OF CONCRETE STRUCTURE
flexibility, such as high-rise buildings under seismic load, and particular provisions have to be made if reinforced concrete is used.
(4)Locally available resources. It is always possible to make use of the local resources of labour and materials such as fine and coarse aggregates. Only cement and reinforcement need to be brought in from outside provinces.
(5)Cost effective. Comparing with steel structures, reinforced concrete structures are cheaper.
(6)Large dead mass, The density of reinforced concrete may reach 2400~2500kg/pare with structures of other materials, reinforced concrete structures generally have a heavy dead mass. However, this may be not always disadvantageous, particularly for those structures which rely on heavy dead weight to maintain stability, such as gravity dam and other retaining structure. The development and use of light weight aggregate have to a certain extent make concrete structure lighter.
毕 业 设 计（论 文）外 文 参 考 资料及译文
译文题目： DESIGN OF REINFORCED CONCRETE STRUCTURES
原文：
DESIGN OF REINFORCED CONCRETE STRUCTURES
1. BASIC CONCERPTS AND CHARACERACTERISTICS OF
the same size but has to steel reinforcing bars (2
φ 16) embedded at the bottom under a un
distributed load q is shown in Fig.1.1(b). The reinforcing bars take up the tension there after the
For example, a plain concrete beam under a uniformly distributed load q is shown in Fig .
1.1(a), when the distributed load increases and reaches a value q=1.37KN/m , the tensile region at the mid-span will be cracked and the beam will fail suddenly . A reinforced concrete beam if
concrete cracking. The thermal expansion coefficients of the two materials are 1.210-5K-1 for-×5~1.5 ×10-5K-1 for concrete .
Generally speaking, reinforced structure possess following features :
concrete is cracked. When the load q is increased, the width of the cracks, the deflection and the
stress of steel bars will increase . When the steel approaches the yielding stress ?y , the
cement mix and results in a hardened concrete. It is generally known that concrete has high compressive strength and low resistance to tension. Its tensile strength is approximately
REINFORCED CONCRETE
Plain concrete is formed from hardened mixture of cement, water , fine aggregate , coarse
aggregate (crushed stone or gravel ) , air and often other admixtures . The plastic mix is placed and consolidated in the formwork, then cured to accelerate of the chemical hydration of hen
Concrete and reinforcement can work together because there is a sufficiently strong bond
between the two materials, there are no relative movements of the bars and the surrounding
(7)Long curing period.. It normally takes a curing period of 28 day under specified conditions for concrete to acquire its full nominal strength. This makes the progress of reinforced concrete structure construction subject to seasonal climate. The development of factory prefabricated members and investment in metal formwork also reduce the consumption of timber formwork materials.
Fig.1.1Plain concrete beam and reinforced concrete beam Is perhaps one of the most durable materials for construction .It does not rot rust , and is not vulnerable to efflorescence . (2)Fire resistance .Both concrete an steel are not inflammable materials .They would not be affected by fire below the temperature of 200℃ when there is a moderate amount of concrete cover giving sufficient thermal insulation to the embedded reinforcement bars. (3)High stiffness .Most reinforced concrete structures have comparatively large cross sections .As concrete has high modulus of elasticity, reinforced concrete structures are usually stiffer than structures of other materials, thus they are less prone to large deformations, This property also makes the reinforced concrete less adaptable to situations requiring certain
one-tenth of its compressive strength. Consequently, tensile reinforcement in the tension zone has to be provided to supplement the tensile strength of the reinforced concrete section.
(8)Easily cracked. Concrete is weak in tension and is easily cracked in the tension zone. Reinforcing bars are provided not to prevent the concrete from cracking but to take up the tensile force. So most of the reinforced concrete structure in service is behaving in a cracked state. This is an inherent is subjected to a compressive force before working load is applied. Thus the compressed concrete can take up some tension from the load.